A tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic materials and their preparation methods

Abstract

This invention discloses a tungsten bronze type Bi 3+ / Zr 4+ A double-doped sodium silver strontium niobate lead-free ceramic material and its preparation method. The general structural formula of the ceramic material is (Sr 2‑x Bi x Ag 0.2 Na 0.8 (Nb) 4.8‑ x Zr x Sb 0.2 )O 15 Where x ranges from 0.03 to 0.15, the present invention prepares the material through batching, ball milling, pre-firing, secondary ball milling, sieving, pressing, and sintering. The preparation method of the present invention is simple, low-cost, highly reproducible, and has a high yield. The resulting ceramic material maintains high energy storage efficiency while achieving high energy storage density and high power density. When x = 0.05, its breakdown electric field reaches as high as 360 kV / cm, and the effective energy storage density is 3.61 J / cm³. 3 The current density can reach 1422.29 A / cm² at room temperature and an electric field strength of 220 kV / cm. 3 The power density is 159 MW / cm². 3 .

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, and relates to tungsten bronze structured energy storage ceramic materials, specifically a tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material and its preparation method. Background Technology

[0002] Dielectric energy storage ceramic materials achieve energy storage by polarizing the dielectric, causing a large amount of charge to accumulate on the electrode surface, thereby forming an electric field. Because the formation of the electric field does not involve chemical reactions, and the energy accumulation process does not involve the diffusion of matter, there are no safety hazards such as leakage, fire, or explosion, making them safer and more reliable. Moreover, among numerous energy storage materials and devices, dielectric capacitors show great application potential in electric vehicles, smart grids, aerospace, high-energy weapons, and green new energy technologies due to their advantages such as fast charging and discharging speeds, high power density, long safe lifespan, and suitability for extreme high-temperature and high-pressure environments. High-performance dielectric materials are the core of dielectric capacitors, mainly classified into three categories: thin films, polymer-based films, and ceramics. Lead-free dielectric ceramics have greater advantages in practical applications due to their simple preparation process, low cost, good temperature stability and fatigue resistance, environmental friendliness, and ease of processing into chip capacitors. However, the relatively low energy storage performance of existing lead-free dielectric ceramic capacitors cannot meet the demands of miniaturization, lightweighting, and integration of energy storage electronic devices. Therefore, the development of lead-free ceramic dielectric materials with high energy density and high power density is becoming increasingly urgent. However, the low energy density and lead-containing nature of currently used energy storage ceramic materials hinder their application. In recent years, lead-free ceramic materials have begun to replace lead-containing materials, the most typical being perovskite lead-free energy storage ceramic materials. Tungsten bronze ferroelectric materials are the second largest ferroelectric materials after perovskite structures, possessing a moderate dielectric constant, very low dielectric loss, and flexible structural adjustability, making them a promising class of energy storage materials. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a tungsten bronze-type Bi material with high energy storage density and high power density. 3+ / Zr 4+ A double-doped sodium silver strontium niobate lead-free ceramic material and its preparation method are presented. The preparation method is simple, reproducible, and low in cost.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A tungsten bronze type Bi 3+ / Zr 4+ A lead-free ceramic material doped with sodium silver strontium antimonate niobate (Sr) is described, with the general structural formula (Sr).2-x Bi x Ag 0.2 Na 0.8 (Nb) 4.8-x Zr x Sb 0.2 )O 15 ,in x The value ranges from 0.03 to 0.15.

[0006] Preferred, x The value is 0.05.

[0007] This invention also protects a tungsten bronze type Bi as described above. 3+ / Zr 4+ A method for preparing a double-doped sodium strontium antimonate silver lead-free ceramic material, characterized by comprising the following steps:

[0008] Step 1: According to (Sr 2-x Bi x Ag 0.2 Na 0.8 (Nb) 4.8-x Zr x Sb 0.2 )O 15 According to the stoichiometric ratio, SrCO3, Bi2O3, Ag2O, Na2CO3, Nb2O5, Sb2O3 and ZrO2 powder raw materials were weighed respectively, put into a ball mill jar for ball milling, and dried to obtain a raw material mixture;

[0009] Step 2: Place the raw material mixture into an alumina crucible, then place the crucible in a box furnace and pre-calcine at 1130-1170℃ for 5-8 hours. After ball milling and drying, the pre-calcined powder is obtained by sieving.

[0010] Step 3: After pressing the pre-calcined powder into tablets, heat the muffle furnace to 680–700 °C at a rate of 8–12 °C / min in an air atmosphere, then heat to 1250–1300 °C at a rate of 2–4 °C / min, hold at this temperature for 4–5 hours, and finally allow it to cool naturally to room temperature to obtain tungsten bronze-type Bi with high energy storage density and high power density. 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0011] Preferably, in step two, the raw material mixture is pre-calcined at 1150 °C for 6 hours.

[0012] Preferably, in step three, the temperature is increased to 700°C at a rate of 10°C / min, then increased to 1270°C at a rate of 3°C / min, and held at that temperature for 4 hours.

[0013] Preferably, the ball milling in steps one and two involves using zirconium balls as the milling balls and anhydrous ethanol as the milling medium, and then fully mixing and milling for 20 to 24 hours.

[0014] Preferably, the drying process described in steps one and two involves placing the sample in an oven and drying it at 70–90°C for 20–24 hours.

[0015] Preferably, the sieving in step two is sieve 120 mesh.

[0016] Preferably, the pre-calcined powder tableting in step three is performed by pressing the powder into a cylindrical blank using a powder tableting machine, and then cold isostatically pressing it for 10-15 minutes under a pressure of 10-15 MPa.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] This invention selects Sr2Ag 0.2 Na 0.8 Nb 4.8 Sb 0.2 O 15 Bi at the A / B sites of the system 3+ / Zr 4+ Double doping, Bi 3+ Bi enters the A site of the tungsten bronze structure 3+ With Pb 2+ Having similar electronic layer structures, Bi 3+ 2p orbitals and O 2- The 2p orbital hybridization enhances the polarity of the A site to compensate for the loss caused by the low polarity element, maintaining a relatively high polarity. P max Zr 4+ The introduction of high-bandgap ions into the B-site of the tungsten bronze structure increases resistivity, improves the insulation performance of the sample, effectively reduces leakage current, and, with appropriate amounts of Bi, enhances the resistivity and insulation performance of the sample. 3+ / Zr 4+ The introduction of [a specific substance] inhibits grain growth, reduces grain size and porosity, and increases the density of the ceramic, thereby improving the breakdown field strength of the ceramic; furthermore, [a specific substance]... 3+ / Zr 4+ The introduction of [a specific ingredient] enhances the local disorder of the material, and the (Sr) prepared in this invention [is related to this invention]. 1.95 Bi 0.05 Ag 0.2 Na 0.8 (Nb) 4.75 Zr 0.05 Sb 0.2 )O 15The energy storage ceramic can achieve a breakdown strength of 360 kV / cm, maintain an energy storage efficiency of 90%, and an energy storage density of 3.61 J / cm³. 3 The power density is 158.98 MW / cm³. 3 ;

[0019] The preparation method of this invention is simple, reproducible, and low in cost. Attached Figure Description

[0020] Figure 1 Comparative Example 1: Strontium sodium antimonate silver tungsten bronze ferroelectric ceramic material and Tungsten bronze type Bi prepared in Examples 1-5 3+ / Zr 4+ XRD pattern of double-doped sodium strontium antimonate silver lead-free ceramic material;

[0021] Figure 2 Comparative Example 1: Strontium sodium antimonate silver tungsten bronze ferroelectric ceramic material and Tungsten bronze type Bi prepared in Examples 1-5 3+ / Zr 4+ Unipolar hysteresis loop diagram of double-doped sodium strontium antimonate silver lead-free ceramic material under critical breakdown electric field;

[0022] Figure 3 Comparative Example 1: Strontium sodium antimonate silver tungsten bronze ferroelectric ceramic material and Tungsten bronze type Bi prepared in Examples 1-5 3+ / Zr 4+ Weber distribution of double-doped sodium strontium antimonate silver lead-free ceramic material;

[0023] Figure 4 Comparative Example 1: Strontium sodium antimonate silver tungsten bronze ferroelectric ceramic material and Tungsten bronze type Bi prepared in Examples 1-5 3+ / Zr 4+ A comparison of the effective energy storage density and energy storage efficiency of double-doped sodium silver strontium niobate ceramic materials under the critical breakdown electric field.

[0024] Figure 5 This is a tungsten bronze type Bi with high energy storage density and high power density prepared in Example 2. 3+ / Zr 4+ Current curves of double-doped sodium silver strontium niobate ceramic material under underdamped conditions with different electric field strengths;

[0025] Figure 6 This is a tungsten bronze type Bi with high energy storage density and high power density prepared in Example 2. 3+ / Zr 4+ Current curves showing the discharge current density and discharge power density as a function of electric field strength for a double-doped sodium strontium antimonate silver lead-free ceramic material. Detailed Implementation

[0026] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0027] Example 1

[0028] Step 1: According to (Sr 1.97 Bi 0.03 Ag 0.2 Na 0.8 (Nb) 4.77 Zr 0.03 Sb 0.2 )O 15 According to the stoichiometric ratio, 8.4711 g of SrCO3 (99.95% purity), 0.2035 g of Bi2O3 (99.999% purity), 1.2344 g of Na2CO3 (99.99% purity), 0.6767 g of Ag2O (99.7% purity), 18.4580 g of Nb2O5 (99.99% purity), 0.8488 g of Sb2O3 (99.99% purity), and 0.1076 g of ZrO2 (99.99% purity) were weighed into a nylon can, ball-milled for 24 hours at 401 rpm using zirconium balls as grinding balls and anhydrous ethanol as the ball milling medium, dried at 80 ℃ for 24 hours, and ground in a mortar for 30 minutes to obtain the raw material mixture.

[0029] Step 2: Place the raw material mixture in an alumina crucible, compact it with an agate rod, cover it, place it in a resistance furnace, heat it to 1150 ℃ at a heating rate of 3 ℃ / min, hold it at that temperature for 6 hours, let it cool naturally to room temperature with the furnace, remove it from the furnace, grind it with a mortar for 30 minutes, and then ball mill it a second time according to the method in Step 1 for 20 hours. Place it in a drying oven and dry it at 80 ℃ for 24 hours. Grind it again with a mortar for 10 minutes, and pass it through a 120-mesh sieve to obtain pre-calcined powder.

[0030] Step 3: Place the pre-calcined powder into a stainless steel mold with a diameter of 11.5 mm, and press it into a cylindrical blank with a thickness of 1.3 mm using a powder press without applying pressure. Place the cylindrical blank in a cold isostatic press and cold isostatically press it for 15 minutes at a pressure of 15 MPa. Place the cylindrical blank on a zirconia plate, and place the zirconia plate in an alumina sealed crucible. Heat the zirconia plate to 700 ℃ at a heating rate of 10 ℃ / min, and then heat it to 1270 ℃ at a heating rate of 3 ℃ / min. Hold the temperature for 4 hours, and then allow it to cool naturally to room temperature in the furnace to obtain tungsten bronze type Bi. 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0031] Example 2

[0032] In step one of this embodiment, according to (Sr1.95 Bi 0.05 Ag 0.2 Na 0.8 (Nb) 4.75 Zr 0.05 Sb 0.2 )O 15 According to the stoichiometric ratio, 8.3728 g of SrCO3 (99.95% purity), 0.3386 g of Bi2O3 (99.999% purity), 1.2326 g of Na2CO3 (99.99% purity), 0.6757 g of Ag2O (99.7% purity), 18.3536 g of Nb2O5 (99.99% purity), 0.8475 g of Sb2O3 (99.99% purity), and 0.1791 g of ZrO2 (99.99% purity) were weighed and placed into a nylon can. The other steps were the same as in Example 1, resulting in a tungsten bronze-type Bi2O3 with both high energy storage density and high power density. 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0033] Example 3

[0034] In step one of this embodiment, according to (Sr 1.92 Bi 0.08 Ag 0.2 Na 0.8 (Nb) 4.72 Zr 0.08 Sb 0.2 )O 15 According to the stoichiometric ratio, 8.2259 g of SrCO3 (99.95% purity), 0.5406 g of Bi2O3 (99.999% purity), 1.2299 g of Na2CO3 (99.99% purity), 0.6742 g of Ag2O (99.7% purity), 18.1977 g of Nb2O5 (99.99% purity), 0.8457 g of Sb2O3 (99.99% purity), and 0.2860 g of ZrO2 (99.99% purity) were weighed and placed into a nylon can. The other steps were the same as in Example 1, yielding a tungsten bronze-type Bi... 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0035] Example 4

[0036] In step one of this embodiment, according to (Sr 1.88 Bi 0.12 Ag 0.2 Na 0.8 (Nb) 4.68 Zr 0.12 Sb 0.2)O 15 According to the stoichiometric ratio, 8.0311 g of SrCO3 (99.95% purity), 0.8086 g of Bi2O3 (99.999% purity), 1.2263 g of Na2CO3 (99.99% purity), 0.6722 g of Ag2O (99.7% purity), 17.9909 g of Nb2O5 (99.99% purity), 0.8432 g of Sb2O3 (99.99% purity), and 0.4277 g of ZrO2 (99.99% purity) were weighed and placed into a nylon can. The other steps were the same as in Example 1, yielding a tungsten bronze-type Bi... 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0037] Example 5

[0038] In step one of this embodiment, according to (Sr 1.85 Bi 0.15 Ag 0.2 Na 0.8 (Nb) 4.65 Zr 0.15 Sb 0.2 )O 15 According to the stoichiometric ratio, 7.8857 g of SrCO3 (99.95% purity), 1.0085 g of Bi2O3 (99.999% purity), 1.2236 g of Na2CO3 (99.99% purity), 0.6708 g of Ag2O (99.7% purity), 17.8366 g of Nb2O5 (99.99% purity), 0.8414 g of Sb2O3 (99.99% purity), and 0.5334 g of ZrO2 (99.99% purity) were weighed and placed into a nylon can. The other steps were the same as in Example 1, yielding a tungsten bronze-type Bi... 3+ / Zr 4+ Double-doped sodium strontium antimonate silver lead-free ceramic material.

[0039] Comparative Example 1

[0040] According to Sr2Ag 0.2 Na 0.8 Nb 4.8 Sb 0.2 O 15According to the stoichiometric ratio, 0.6190 g of SrCO3 with a purity of 99.95%, 0.6782 g of Ag2O with a purity of 99.7%, 1.2371 g of Na2CO3 with a purity of 99.99%, 18.6150 g of Nb2O5 with a purity of 99.99%, and 0.8506 g of Sb2O3 with a purity of 99.99% were weighed out respectively. The other steps were the same as in Example 1, and tungsten bronze type strontium sodium antimonate silver lead-free ceramic material was obtained.

[0041] The tungsten bronze type Bi prepared in Examples 1-5 above 3+ / Zr 4+ The double-doped strontium sodium silver niobate lead-free ceramic material and the strontium sodium silver tungsten bronze energy storage ceramic material prepared in Comparative Example 1 were used. The ceramic sheet thickness was polished to 150 μm. Gold electrodes were deposited on the upper and lower surfaces of the ceramic using an ion sputtering instrument. The ion sputtering conditions included: a gold target, a current of 15 mA, and a time of 200 ms. The ferroelectric properties were then tested at room temperature and a frequency of 10 Hz. The phase structure and properties were characterized using a SmartLab9 X-ray diffractometer (Rigaku Corporation, Japan) and a ferroelectric testing instrument (Radiant Corporation, USA). Relevant performance parameters were calculated using the following formula:

[0042] Effective energy storage density W rec :

[0043] Total energy storage density W total :

[0044] In the formula: P m For maximum polarization intensity, P r The remanent polarization intensity, E The electric field strength is shown in the figure. Figures 1-3 .

[0045] Depend on Figure 1 It can be seen that a small amount of Na appeared in the ceramic materials prepared in Examples 3-5. 0.5 Sr 0.25 Nb5O 15 The second phase, the ceramic materials prepared in Examples 1-2 and Comparative Example 1, are pure tungsten bronze structures.

[0046] Depend on Figure 2 It is evident that with Bi 3+ / Zr 4+With the increase of doping amount, the breakdown field strength of the ceramic material prepared in Example 1 is significantly improved, from 230 kV / cm in Comparative Example 1 to 285 kV / cm. The increase in breakdown field strength leads to a significant increase in energy storage density.

[0047] The ceramic material prepared in Example 2, compared to that in Example 1, exhibits higher maximum polarization intensity ( P max While the residual polarization intensity remains basically unchanged, P r The breakdown field strength is significantly reduced, and the breakdown field strength is increased to 380 kV / cm, resulting in higher effective energy storage density and high energy storage efficiency for the ceramic material. Furthermore, through multiple electrical breakdown experiments, and by utilizing the Weiber distribution to determine its reliable breakdown field strength value, such as… Figure 3 As shown, and based on the experimental results obtained above, under this electric field strength, P - E Curve testing, ceramic materials of Examples 3-5 compared to ceramic material of Example 2. P max The energy density decreases slightly due to the precipitation of the second phase, which reduces the breakdown electric field and consequently lowers the energy storage density.

[0048] Depend on Figure 4 It can be seen that the effective energy storage density of the ceramic material prepared in Comparative Example 1 is 1.91 J / cm³. 3 The energy storage efficiency is 88.8%, according to Bi 3+ / Zr 4+ After dual doping at the A / B sites, the energy storage density and energy storage efficiency of the ceramic materials prepared in Examples 1-3 were significantly improved, with energy storage density ranging from approximately 2.63 to 3.61 J / cm³. 3 The energy storage efficiency is approximately 85.1%–91.6%, especially when Bi 3+ / Zr 4+ When the doping concentration is 0.05, the effective energy storage density of the ceramic reaches as high as 3.61 J / cm³. 3 The energy storage efficiency remains at 90%.

[0049] The tungsten bronze type Bi prepared in Example 2 3+ / Zr 4+ The surface of the double-doped sodium strontium antimonate niobate silver lead-free ceramic material was ground, polished, ultrasonically cleaned, and then coated with silver paste on both the upper and lower surfaces. It was then placed in a muffle furnace at 840 ℃ for 30 minutes and allowed to cool naturally to room temperature. Its charge-discharge performance was then tested under different electric field strengths, and the charge-discharge characteristics were calculated using the following formula:

[0050] Current density C D :

[0051] Power density P D :

[0052] in, C D and P D These represent current density and power density, respectively. I max Indicates the maximum current density. E S represents the electric field strength, and S represents the electrode area, such as Figures 5-6 The underdamped discharge curves of the ceramic material prepared in Example 2 were measured at room temperature and under electric fields of 120–220 kV / cm. The current density and power density values ​​were calculated from the charge-discharge characteristics of the underdamped discharge curves. The current density at room temperature and an electric field strength of 220 kV / cm reached 1422.29 A / cm. 2 The power density is 158.98 MW / cm³. 3 This technology meets the practical application requirements of ceramic energy storage capacitors and is expected to be used in the electronic ceramics market.

Claims

1. A tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, The ceramic material has a general structure of (Sr 2-x Bi x Ag 0.2 Na 0.8 )(Nb 4.8-x Zr x Sb 0.2 )O 15 , wherein x has a value of 0.03 to 0.

05. The preparation method comprises the following steps: Step one, according to the stoichiometric ratio of (Sr 2-x Bi x Ag 0.2 Na 0.8 )(Nb 4.8-x Zr x Sb 0.2 )O 15 , respectively, SrCO3, Bi2O3, Ag2O, Na2CO3, Nb2O5, Sb2O3, ZrO2 powder raw materials are weighed, the weighed raw materials are put into a ball mill tank for ball milling and drying to obtain a raw material mixture; Step two, the raw material mixture is put into an alumina crucible, the crucible is placed in a box furnace, pre-sintering is carried out at 1130-1170 DEG C for 5-8 hours, ball milling, drying, and then screening are carried out to obtain pre-sintered powder; Step three, after the pre-burned powder is pressed into a tablet, the muffle furnace is heated to 680-700 DEG C at a speed of 8-12 DEG C / min under air atmosphere, then heated to 1250-1300 DEG C at a heating rate of 2-4 DEG C / min, and kept for 4-5 hours, and finally naturally cooled to room temperature, to obtain a tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium antimony niobate silver lead-free ceramic material The pre-sintered powder is pressed into a cylindrical body by a powder tablet press, and then cold isostatic pressing is carried out at a pressure of 10-15 MPa for 10-15 minutes.

2. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, x the value of 0.

05.

3. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, In step two, the raw material mixture is pre-sintered at 1150 DEG C for 6 hours.

4. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, In step three, the temperature is raised to 700 DEG C at a rate of 10 DEG C / min, then the temperature is raised to 1270 DEG C at a rate of 3 DEG C / min, and the temperature is kept for 4 hours.

5. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, In step one and step two, the ball milling is carried out by using zirconium balls as grinding balls and anhydrous ethanol as ball milling medium, and the ball milling is carried out for 20-24 hours.

6. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, In step one and step two, the drying is carried out in an oven at 70-90 DEG C for 20-24 hours.

7. The tungsten bronze type Bi 3+ / Zr 4+ Double-doped sodium strontium silver antimonium niobate lead-free ceramic material, characterized in that, In step two, the screening is carried out through a 120 mesh screen.

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